The investigation into Russian interference in the 2016 election is usually shrouded in mystery. Special counsel Robert Mueller hates leaks, and he hasn't commented publicly since he started the job, but we got a glimpse into his work today after The New York Times published about four dozen questions the paper says Mueller wants to ask President Trump. Here to talk about them is NPR justice correspondent Carrie Johnson.

Hey there, Carrie. Welcome to the studio.

CARRIE JOHNSON, BYLINE: Hi, Audie.

CORNISH: So I think there are 49 questions. I don't know why they couldn't come up with one more. But what stands out to you?

JOHNSON: There are lots of questions about President Trump's response to this investigation, taking into account possible obstruction of justice. Robert Mueller wants to know why the president fired FBI Director James Comey last year, what Trump knew about the FBI's work on Russia before he got rid of Comey at the time. The Mueller team also wants to know about the president's volatile relationship with his attorney general, Jeff Sessions, who recused himself from this Russia probe and once offered to resign. And then there are questions about former National Security Adviser Michael Flynn. Flynn left the White House under pressure last year. But did Trump know that Flynn had lied to the FBI about his dealings with the Russian ambassador? And did Trump learn about that before he fired Comey and asked Comey to go easy on Flynn?

CORNISH: And the response from the president - not to the questions, but to this report?

JOHNSON: Yeah, Trump has called this investigation a witch hunt. He went on Twitter to say it would seem very hard to obstruct justice for a crime that never happened. But, in fact, it is against the law to interfere with an investigation, even if there is no underlying crime. The president's wrong about that. Trump also says there's no hint of collusion in this list of questions.

Actually, not so fast - there are a bunch of questions about the Trump Organization's business dealings in Russia, what the president may have known about his son Donald Jr.'s contacts with the Russians, about what his son-in-law, Jared Kushner, may have been doing with Russians during the campaign, and also a question about what former campaign chairman Paul Manafort may have been doing out - to reach out to Russia during the campaign. Remember, Audie, Robert Mueller has already got cooperation from Michael Flynn, from campaign adviser George Papadopoulos and from Manafort's right-hand man Rick Gates, so prosecutors surely know more than they're saying and more than they're hinting in these questions.

CORNISH: Why are we seeing these questions now, essentially in the middle of an investigation, in the middle of a negotiation about whether the president would answer - right? - in this form?

JOHNSON: Well, The New York Times isn't saying where they got this list, but they do say it came from notes that Trump's lawyers took in a meeting with the special counsel team. These are not an exhaustive list of questions. But if people close to the president are trying to send him a message that he should avoid talking to Mueller, that might precipitate this kind of leak. In other words, here's a bunch of questions the special counsel team wants to ask you; do you really want to sit down for a voluntary interview and be forced to answer all these questions? The rub for the president, Audie, is if he doesn't sit for a voluntary interview, it's always possible the Mueller team could subpoena him and try to force him to talk.

CORNISH: In the meantime, the man overseeing the Russia investigation, Deputy Attorney General Rod Rosenstein, had some choice words for lawmakers, specifically. What did he have to say?

JOHNSON: Yeah, these were very bold remarks by Rod Rosenstein at the Newseum in honor of Law Day today. He glossed over tensions with the White House. Of course, he's been a frequent target of the president. But he did have a bone to pick with Congress. Some House Republicans have drafted articles of impeachment against Rod Rosenstein. Rosenstein told the audience today, no one in Congress had enough courage to attach their name to that document. And he said the Department of Justice is not going to be extorted for documents about the Russia probe or anything else.